Dynamic flow sensor

ABSTRACT

A flow sensing and control arrangement by which a jet of line fluid is continuously directed across a flow line against a biased pressure responsive device which moves to initiate a control function upon diffusion of the jet when line flow occurs. In a preferred embodiment, the pressure-responsive device controls a valve, normally closed by the jet but which opens upon the presence of line flow to introduce an additive to the flow line.

United States Patent [72} lnventor William L. Livingston Sharon, Mass.[21] Appl. No. 768,862 [22 Filed Oct. 18, 1968 [45] Patented Jan. 26,1971 [73] Assignee Factory Mutual Research Corporation Turnpike, Mass. acorporation of Massachusetts [54] DYNAMIC FLOW SENSOR 13 Claims, 1Drawing Fig.

[52] U.S. Cl 137/7, 137/81.5: 169/15 [51] Int. Cl F15c 3/00, F15c 3/04[50] Field of Search 137/7, 10, 13,815; 169/15, 14,8,2

[56] References Cited UNITED STATES PATENTS 1,619,130 3/1927 Jones137/466 ADDITBI'VE CARRIER Primary Examiner-Samuel Scott Attorney-Lane,Aitken, Dunner and Ziems ABSTRACT: A flow sensing and controlarrangement by which a jet of line fluid is continuously directed acrossa flow line against a biased pressure responsive device which moves toinitiate a control function upon diffusion of the jet when line flowoccurs. In a preferred embodiment, the pressureresponsive devicecontrols a valve, normally closed by the jet but which opens upon thepresence of line'flow to introduce an additive to the flow line.

BACK- UP POWER DYNAMIC FLOW SENSOR BACKGROUND OF THE INVENTION DETAILEDDESCRIPTION OF THE PREFERRED EMBODIMENT As shown in the drawing, thedynamic flow sensor of this in- Thls mvermon felines to flow sensors"and more 5 vention is shown schematically as part of a fireextinguishing particularly, it concerns a novel arrangement for sensingfluid flow in a pipe line and actuating a control mechanism in responseto the sensed flow. The arrangement has particular utility in certaintypes of fire extinguishing systems to be described but otherapplications are contemplated.

In a copending application entitled Method of Controlling Fire, Ser. No.766,475, filed Oct. 10, 1968, by the inventors William L. Livingston andRussell W. Pierce and assigned to the assignee of the present invention,a fixed fire extinguishing system for enclosures is described and inwhich a water swellable polymer is mixed with water when the system isactivated so that an ablative gel is dispensed from sprinkler headslocated over the fire. The primary advantage of such a system is thatthe ablative gel is substantially more viscous than plain water andtends to cling to the surfaces on which it is sprayed. Consequently, asignificantly lower quantity of extinguishant is required to put out afire than is required with plain water, thereby enabling system designswith lower flow capacity than systems which have used plain water. Givensuch a system design, however, it becomes apparent that the introductionof gelling agent into the water line at the instant the system isactivated is essential to proper operation.

Also it should be borne in mind that fire extinguishing systems ingeneral, remain inactive for long periods of time often exceedingseveral years duration. Under such circumstances, conventional items offluid handling hardware can and most likely will become deteriorated dueto corrosion and the like, posing the possibility of a malfunction atthe time when operation of them is called for. Malfunctioning of thistype cannot be tolerated in fire extinguishing systems if their intendedpurpose is to be fulfilled.

SUMMARY OF THE INVENTION In accordance with the present invention, adynamic or failsafe flow sensing arrangement is provided by which thevelocity head of a fluid jet directed transversely of a pipe line isemployed to retain a pressure-responsive diaphragm in an inactiveposition. This condition will be maintained until fluid flow develops inthe pipe line and diffuses the jet to upset the balance of pressureacross the diaphragm. When used in a fire extinguishing system of thetype mentioned above, the diaphragm is used as an actuator for a valvewhich controls the introduction of the gelling agent additive.Accordingly the valve remains closed when the system is inactive, butopens immediately when flow occurs in the pipe line to provide theablative gel extinguishant.

Among the objects of the present invention are therefore; the provisionof a dynamic flow sensor for pipe lines in which the diffusion of afluid jet by fluid flow is employed as a flow signal source; theprovision of a flow sensing device particularly suitable for use inoperating a valve for controlling the introduction of an additive to aflow line upon the development of fluid flow therein; the provision of aflow sensor of the type aforementioned which is capable of varyingdegrees of sensitivity; and a dynamic flow sensor of the typeaforementioned which is particularly suitable for the introduction of aablative gel additive to a water line in fire extinguishing systems.Other objects and further scope of applicability of the presentinvention will become apparent to those skilled in the art from thedescription to follow taken in conjunction with the accompanyingdrawing.

BRIEF DESCRIPTION OF THE DRAWING The single FIG. in the drawing is aschematic view illustrating in cross section the operative elements ofthe flow sensing and control device of the present invention in a fireextinguishing system.

system including a plurality of sprinkler heads 10 located in a watersource 12 by a pipe line 14v In accordance with conventional practice,the system is provided with temperature detector (not shown) located inthe vicinity of the sprinkler heads 10 so that upon the development of afire in the space protected the system is activated automatically tosupply the sprinklers with an extinguishant to put out the fire. In theparticular system contemplated, the extinguishant is an ablative gelformed by a mixture of water from the source 12 and a gelling agentintroduced into the pipe line as an additive and carrier mixturesupplied from a reservoir 16.

The reservoir 16 is in fluid communication with the pipe line 14 by wayof a line 18 and a valve 20 having an annular inlet chamber 22positioned about a concentric outlet tube 24 in direct communicationwith a distributing head 26. Communication between the inlet chamber 22and the outlet pipe 24 is controlled by a diaphragm valve 28 which, whenclosed, seats on the upper end of the outlet pipe 24 as shown in thedrawing.

It will be understood that the additive and carrier mixture in thereservoir 16 is under a sufficient head so that when the valve 28 opens,the additive and carrier will flow through the valve and into the pipe14 through the distributor head 26 to be mixed with the water in thepipe. To facilitate the introduction of the gelling agent, a plate 30 ispositioned around the distributor head to create an area of turbulenceupon flow in the pipe line 14 in a direction from the source 12 to thesprinkler heads 10. The turbulence will provide a zone of reducedpressure to facilitate an introduction and mixing of the additive andcarrier with the water in the pipe line 14.

As pointed out above, it is imperative that the additive and carrier beintroduced into the pipe line 14 when the fire extinguishing system isactivated to effect water flow in the latter pipe line. At all othertimes, the valve 28 remains closed to prevent additive introduction intothe water within the pipe line 14.T0 enable this mode of operation, thevalve 28 is coupled by a connector rod 32 to a flexible diaphragm 34establishing a pair of chambers 36 and 38 in a closed vessel 40. It willbe noted that the chamber 36 is in fluid communication with the pipeline 14 by way of a tube 42 having a flow restrictor 44 therein, whereasthe chamber 38 is also in communication with the pipe line 14 through atube 46. Further, it will be noted that the diaphragm 34 is urgedupwardly by a helical compression spring 48, thereby biasing the valve28 to its open position. In light of the static pressure balance acrossthe diaphragm 34 through the tubes 42 and 46, static pressure in thepipe line 14 does not have an effect on the positioning of the diaphragm34 and thus of the valve 28.

To constrain the valve 28 in a closed position, a velocity head isimposed on the chamber 36 tending to overcome the bias of the spring 48and retain the valve 28 in its closed position. This velocity head isdeveloped by a continuously operating pump 50 which circulates water inthe pipe line 14 through a nozzle 52 across the pipe line 14 and intothe tube 54 communicating with the chamber 36. The pump 50 is drivencontinuously by an electric motor 56 connected witha power supply bylines 58. A source of backup power 60, such as a battery or the like, isconnected to the lines 58 to keep the motor running in the event of apower failure.

Thus it will be appreciated that so long as the pump 50 remains inoperation the velocity head or dynamic pressure of the fluid or waterjet issuing from the nozzle 52 will be transmitted to the chamber 56 tomaintain the diaphragm 34 against the bias of the spring 48. Therestrictor 44 in the tube chamber 36 to avoid minor fluctuations ornoise" that may be present in the system. Also, the size of therestrictor 44 can be selected to vary the velocity head imposed on thediaphragm 34 and thus control the sensitivity of the diaphragm.

When the fire extinguishing system is activated so that water from thesource 12 flows through the pipe line 14 to the sprinkler heads 10, thefluid jet passing from the nozzle 52 will be diffused. As a result, thevelocity head thereof imposed upon the diaphragm 34 in the chamber 36will be removed. The spring 48 then will move the diaphragm 34 upwardlyto open the valve 28 and permit the additive and carrier to pass fromthe reservoir 16 through the valve 20 and distributor head 26 into thepipe line M.

Thus it will be appreciated that an extremely effective fluid flowsensor and control apparatus is provided by which the above-mentionedobjectives are completely fulfilled. Though the system described hasparticular utility in fire extinguishing systems where an additive isintroduced upon activation of the system, it will be appreciated thatthe flow sensing and control features of this invention can be used inany application where it is required to introduce an agent into a flowline upon the existence of fluid flow therein. Also the sensing featureof this invention could be used solely to provide indication of fluidflow .by coupling the diaphragm 34 to an appropriate switch mechanism orthe like in a circuit with an indicating device.

It is intended that the foregoing description is illustrative of apreferred embodiment only, not limiting, and that the true spirit andscope of the present invention be determined by reference to theappended claims.

lclaim:

l. Apparatus for sensing fluid flow, said apparatus comprising: aconduit normally containing fluid under static conditions and throughwhich conduit said fluid flows during passage thereof from a source to apoint remote from said source; means to develop a continuous jet offluid across at least a portion of the conduit; and pressure sensitivemeans movable between first and second positions, said pressuresensitive means normally being retained in said first position by saidjet and movable to said second position upon diffusion of said jet duetofluid flow in said conduit.

2. The apparatus recited in claim 1 wherein said means to develop acontinuous jet comprises a pump having an intake in communication withthe conduit and a nozzle outlet directed transversely of the conduit. 1

3. The apparatus recited in claim 1 including a valve for controllingthe admission of an additive to thefluid in said conduit, said pressuresensitive means being coupled to said valve, said valve being closedwhen said pressure sensitive means is in said first position and openedwhen said pressure sensitive means is in said second position.

4. The apparatus recited in claim 1 when said pressure sensitive meansis a diaphragm and including means to bias said diaphragm to said secondposition.

5. The apparatus recited in claim 2 wherein said biasing means includesa compression spring.

6. The apparatus recited in claim 2 including means defining a chamberon each side of said diaphragm, one of said chambers including saidbiasing means and the other of said chambers being exposed tosaid jet.

7. The apparatus recited in claim 6 including a flow line having one endopening to the-conduit at a'location so that the said flow line receivessaid jet, the opposite end of said flow line opening to the other ofsaid chambers.

8. The apparatus recited in claim 7including a vent line ex tendingbetween each of said chambers and the conduit, the vent line connectedto the other of said chambers having a flow restrictor therein todevelop a back pressure in the other of said chambers acting on saiddiaphragm as a result of said jet.

9. In a fire extinguishing system of the type in which an ablative gelformed of a mixture of water and a gelling agent is sup plied as anextinguishant to sprinkler heads upon the existence of a fire in thevicinity of the sprinkler heads, apparatus for introducmg the gellingagent into a water supply line upon the existence of water flow in theline, said apparatus comprising valve-means for controlling admission ofsaid gelling agent tothe pipe line and means for retaining of said valvemeans in a closed position in the absence of water flow in said pipeline and to open said valve upon the existence of water flow in saidpipe line, said last mentioned means including means for directing a jetof water transversely of said pipe line, and means responsive to saidjet to retain said valve in said closed position, whereby diffusion ofsaid jet due. to flow in said pipe line results in said valve moving toits open position.

10. The method of controlling the introduction of an additive to a fluidin a conduit, said method comprising the steps of: directing acontinuous jet of fluid across at least a portion of sajdconduit;developing a continuous output to block the introduction of additive inresponse to the presence of said jet at a point spaced in said conduitfrom the origin of said jet; and initiating the introduction of saidadditive upon the interruption of said output due to diffusion of saidjet by fluid flow in said conduit.

11. The method recited in claim 10 wherein said fluid is water andwherein said additive is a gelling agent.

12. The method recited in claim 11 wherein said conduit supplies anablative gel formed by the mixture of said gelling agent and said waterto the sprinkler heads of a fixed fire extinguishing system.

13. The method of sensing flow of fluid in a conduit said methodcomprising the steps of: continuously directing ajet of fluid across atleast a portion of said conduit; developing a continuous output inresponse to the presence of said jet at a point spaced in said conduitfrom the origin of said jet; and providing a flow signal upon theinterruption of said output due to diffusion of said jet by fluid flowin said conduit.

2. The apparatus recited in claim 1 wherein said means to develop acontinuous jet comprises a pump having an intake in communication withthe conduit and a nozzle outlet directed transversely of the conduit. 3.The apparatus recited in claim 1 including a valve for controlling theadmission of an additive to the fluid in said conduit, said pressuresensitive means being coupled to said valve, said valve being closedwhen said pressure sensitive Means is in said first position and openedwhen said pressure sensitive means is in said second position.
 4. Theapparatus recited in claim 1 when said pressure sensitive means is adiaphragm and including means to bias said diaphragm to said secondposition.
 5. The apparatus recited in claim 2 wherein said biasing meansincludes a compression spring.
 6. The apparatus recited in claim 2including means defining a chamber on each side of said diaphragm, oneof said chambers including said biasing means and the other of saidchambers being exposed to said jet.
 7. The apparatus recited in claim 6including a flow line having one end opening to the conduit at alocation so that the said flow line receives said jet, the opposite endof said flow line opening to the other of said chambers.
 8. Theapparatus recited in claim 7 including a vent line extending betweeneach of said chambers and the conduit, the vent line connected to theother of said chambers having a flow restrictor therein to develop aback pressure in the other of said chambers acting on said diaphragm asa result of said jet.
 9. In a fire extinguishing system of the type inwhich an ablative gel formed of a mixture of water and a gelling agentis supplied as an extinguishant to sprinkler heads upon the existence ofa fire in the vicinity of the sprinkler heads, apparatus for introducingthe gelling agent into a water supply line upon the existence of waterflow in the line, said apparatus comprising valve means for controllingadmission of said gelling agent to the pipe line and means for retainingof said valve means in a closed position in the absence of water flow insaid pipe line and to open said valve upon the existence of water flowin said pipe line, said last mentioned means including means fordirecting a jet of water transversely of said pipe line, and meansresponsive to said jet to retain said valve in said closed position,whereby diffusion of said jet due to flow in said pipe line results insaid valve moving to its open position.
 10. The method of controllingthe introduction of an additive to a fluid in a conduit, said methodcomprising the steps of: directing a continuous jet of fluid across atleast a portion of said conduit; developing a continuous output to blockthe introduction of additive in response to the presence of said jet ata point spaced in said conduit from the origin of said jet; andinitiating the introduction of said additive upon the interruption ofsaid output due to diffusion of said jet by fluid flow in said conduit.11. The method recited in claim 10 wherein said fluid is water andwherein said additive is a gelling agent.
 12. The method recited inclaim 11 wherein said conduit supplies an ablative gel formed by themixture of said gelling agent and said water to the sprinkler heads of afixed fire extinguishing system.
 13. The method of sensing flow of fluidin a conduit said method comprising the steps of: continuously directinga jet of fluid across at least a portion of said conduit; developing acontinuous output in response to the presence of said jet at a pointspaced in said conduit from the origin of said jet; and providing a flowsignal upon the interruption of said output due to diffusion of said jetby fluid flow in said conduit.